"The Last Days of Disco Stick" is the 10th episode of the third season of the American teen drama television series Gossip Girl, and the 53rd episode overall. Written by Leila Gerstein and directed by Tony Wharmby, it originally aired on The CW on November 16, 2009. The episode features a cameo appearance and special performance by Lady Gaga, and marks the last appearance of Hilary Duff on the series. Plot Serena (Blake Lively) continues to have chemistry with Tripp (Aaron Tveit). Serena knew that it was wrong and went to Nate (Chace Crawford) for help. Nate decides to not let Serena out of his sight until Tripp leaves for Washington D.C. the following day. They spend a lot of time together and some chemistry builds there. At a bar, Nate confesses he has always been in love with Serena and leans in to kiss her. As he does this, a distressed Tripp walks in and interrupts. He just learned that it wasn't their grandfather that set up the drowning man in the Hudson River on Election Day, but his wife. Now that his marriage has fallen through, Serena goes to comfort him. Nate urges her not to go, but she insists. Things are awkward between Dan (Penn Badgley), Vanessa (Jessica Szohr), and Olivia (Hilary Duff) now after their threesome. Nate tells Dan that the third person should always be a stranger. Vanessa and Olivia fight over Dan's time and attention. They are all brought together by Blair (Leighton Meester) for a performance. Blair runs another one of her get popular schemes; to get in with the elite of Tisch School of the Arts. They hosted a gathering of actors and writers to perform a play based around pop culture: a modern-day Snow White using the music of Lady Gaga. Blair was originally not invited, but got Olivia to get her in with her connections. Dan brings Vanessa in as the director of the play. Olivia and Vanessa vie for Dan's attention. During one of the scenes, Olivia calls out Dan for having a thing for Vanessa. She leaves, leaving Vanessa to fill in for her as Snow White. When Dan kisses Vanessa, he realizes that he's had feelings for her all along. Unfortunately, Vanessa is interested in some artsy guy from Tisch. Olivia decided to leave NYU, leaving Dan all alone. Blair brought Lady Gaga on stage which really